MUMBAI, India — Indian police searched for clues on Thursday about who was behind three coordinated bomb blasts that killed at least 17 people in Mumbai, the biggest attack since Pakistani-based militants rampaged through the financial hub in 2008.

Mumbai police blamed Wednesday's attacks on the Indian Mujahideen, a shadowy home-grown Islamist group said to have support from militants in Pakistan, according to source-based media reports that could not be independently confirmed.

The government's official press office lowered the death toll to 17 from an earlier figure of 21 killed, although the number may change again.

Prithviraj Chavan, chief minister of Maharashtra state, told Indian TV station NDTV that the blasts occurred between 6:50 p.m. and 7:04 p.m. local time (9:20 to 9:34 a.m. ET).

Blood-covered bodies lay on Mumbai streets and people hugged and wept. Others carried the wounded to taxis. Crowds gathered in the blast areas as police questioned witnesses, and bomb squads inspected the undercarriages of vehicles searching for clues and other explosives.

It was the first terrorist attack on the city since 10 militants laid siege to Mumbai for 60 hours in November 2008, killing 166 people and escalating tensions with Pakistan. There was no immediate claim of responsibility.

"I have appealed to the people of Mumbai to maintain peace and calm," Chavan told NDTV. "We will face this calamity and challenge to our sovereignty ... we will fully meet this challenge."

He called the explosions "an attack on the heart of India"

The first blast struck the Jhaveri Bazaar at 6:54 p.m., tearing through the famed jewelry market. A minute later, a second blast hit the busy business district of Opera House, several miles away in southern Mumbai. At 7:05 p.m., the third bomb exploded in the crowded neighborhood of Dadar in central Mumbai, according to police.

The Zaveri Bazaar blast took place in an umbrella kept at the crowded Kahu Gali, a street of eateries where many commuters stop to snack before catching their local trains home, NDTV reported. The Dadar West explosion took place in a meter box on an electric pole near a bus stop, it said. The Opera House blast, the most powerful of the three, took place at Prasad Chamber building.

At least one car and a motorbike were used in the coordinated attacks in which improvised explosive devices were believed to have been used, officials said.

A bomb that failed to go off was found in Dadar, NDTV reported, and a bomb disposal squad was working to defuse it.

Because of the close timing of the bomb blasts, "we infer that this was a coordinated attack by terrorists," Home Minister Palaniappan Chidambaram said, adding that Mumbai was put on high alert.

Prime Minister Manmohan Singh condemned the blasts and also appealed to the people of Mumbai "to remain calm and show a united face."

In Washington, President Barack Obama also condemned the "outrageous attacks"

"The American people will stand with the Indian people in times of trial, and we will offer support to India's efforts to bring the perpetrators of these terrible crimes to justice," he said in a statement. "I have no doubt that the India will overcome these deplorable terrorist attacks."

The U.S. State Department said it would offer India assistance in its response and investigation of the Wednesday attack, just as it did in 2008.

The State Department said the blast would not change Secretary Hillary Clinton's already scheduled visit to New Delhi July 18-20, NBC News reported.

"I believe it is more important than ever that we stand with India, deepen our partnership and reaffirm our commitment to the shared struggle against terrorism," Clinton
said in a news conference (on this page)
with the Russian foreign minister.

The U.N. Security Council said it "condemned in the strongest terms" the attacks.

"Any acts of terrorism are criminal and unjustifiable, regardless of their motivation, wherever, whenever and by whomsoever committed," said the Council statement, which was read to reporters by Germany's U.N. ambassador Peter Wittig.

Bodies and blood at the scene
At the site of the first bombing, Jhaveri Bazaar, a witness described two motorcycles exploding in flames and saw at least six bodies.

NDTV said there were reports that six people had died in the blast in Dadar with a further four in the bazaar blast.

Rajanish Kakade
/
AP

Police inspect the site of an explosion at Dadar in Mumbai, India, Wednesday, July 13, 2011.

"We were inside our office when we heard a huge noise. Outside there was a lot of commotion, we can see fire trucks are here and they have taken away two or three bodies," Jasraj Jain, a witness, told CNN-IBN television.

"India is not going to cow down," Cabinet minister Farooq Abdullah said. "Let those perpetrators of this terror remember, we will find them and Inshallah (God willing) we will give them the justice that India believes in."

The Wednesday attack did not appear to involve suicide attackers but consisted of explosives placed in a taxi, a meter box and locations where they could be remotely detonated, said Stratfor, an Austin, Texas-based global intelligence firm.

"This tactic is much more in line with those used by more amateurish groups, such the Indian Mujahideen, who have targeted crowded urban areas before," Stratfor said.

The 2008 attack, which targeted two luxury hotels, a Jewish center and a busy train station, was blamed on the Pakistan-based Lashkar-e-Taiba group, long focused on fighting Indian rule in Kashmir.

The attacks escalated tensions between the nuclear-armed rivals and prompted them to suspend peace talks.

However, the talks have recently resumed.

Strafor also noted that a crisis between India and Pakistan could complicate U.S. plans to withdraw troops from Afghanistan, a strategy that relies on U.S.-Pakistani cooperation to fight terrorism. U.S.-Pakistani collaboration already worries India, Strafor said.

Closed captioning of: Bombs attack Mumbai, killing 21

>> reporter: the bombs were well hidden and coordinated to explode at the height of
mumbai
's evening rush hour. the first exploded in a renowned jewelry market just before
7:00 p.m
. a minute later, a second, more powerful device went off in a crowded
business district
near a
bus station
, one bomb was apparently hidden under an umbrella, the other in an
electric circuit
box. after two back to back explosions, police new
mumbai
was under attack by terrorists. then a third bomb believed to have been in a taxi, exploded downtown. police locked down the city.

>>the entire city of
mumbai
has been put on high alert. i would
appeal to the people
of
mumbai
and people all over the country to remain calm and maintain peace.

>> reporter: so far, no one has claimed responsibility, but suspicion falls on the same pakistan-based group that attacked
mumbai
in
2008
. this time,
mumbai
was better prepared, but the violence would inflame tension between two old enemies, india and pakistan, both
nuclear powers
.
richard engel
, nbc news, cairo.